Reaction processing apparatus

ABSTRACT

A reaction processing apparatus includes: a reaction processing vessel; a first fluorescence detection device that irradiates a sample with first excitation light and detects first fluorescence produced from the sample; and a second fluorescence detection device that irradiates a sample with second excitation light and detects second fluorescence produced from the sample. The wavelength range of the first fluorescence and the wavelength range of the second excitation light overlap at least partially. The first excitation light and the second excitation light flash at a predetermined duty ratio d. The phase difference between the flashing of the first excitation light and the flashing of the second excitation light is set within a range of 2π(pm−Δpm) (rad) to 2π(pm+Δpm) (rad) or within a range of 2π[(1−pm)−Δpm] (rad) to 2π[(1−pm)+Δpm] (rad), where pm=d−d2 and −pm =0.01*pm.

CROSS- REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.17/028,331 filed Sep. 22, 2020, which is a continuation of InternationalApplication No. PCT/JP2019/009902 filed Mar. 12, 2019, claiming prioritybased on Japanese Patent Application No. 2018-056767 filed Mar. 23,2018, the contents of all of which are incorporated herein by referencein their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to reaction processing apparatuses usedfor polymerase chain reactions (PCR).

Background Art

Genetic testing is widely used for examinations in a wide variety ofmedical fields, identification of farm products and pathogenicmicroorganisms, safety assessment for food products, and even forexaminations for pathogenic viruses and a variety of infectiousdiseases. In order to detect with high sensitivity a minute amount ofDNA, methods of analyzing the resultant obtained by amplifying a portionof DNA are known. Above all, a method that uses PCR is a remarkabletechnology where a certain portion of a very small amount of DNAcollected from an organism or the like is selectively amplified.

In PCR, a predetermined thermal cycle is applied to a sample in which abiological sample containing DNA and a PCR reagent consisting ofprimers, enzymes, and the like are mixed so as to cause denaturation,annealing, and elongation reactions to be repeated so that a specificportion of DNA is selectively amplified.

It is a common practice to perform PCR by putting a predetermined amountof a target sample into a PCR tube or a reaction processing vessel suchas a microplate (microwell) in which a plurality of holes are formed.However, in recent years, PCR using a reaction processing vessel (alsoreferred to as “chip”) provided with a micro-channel that is formed on asubstrate is practiced (e.g. Patent Document 1).

[Patent Document 1] Japanese Patent Application

Publication No. 2009-232700

SUMMARY OF THE INVENTION

In PCR where a reaction processing vessel provided with a channel suchas the one described above, a fluorescence detection device may be usedfor the purpose of, e.g., detecting a quantitative change of a sample. Afluorescent dye is added to the sample, and excitation light is appliedto the sample using a fluorescence detection device during PCR so as todetect fluorescence emitted from the sample. Since the intensity offluorescence emitted from the sample increases as the amplification ofthe DNA proceeds, the intensity value of the fluorescence can be used asan index serving as a decision material for the progress of the PCR orthe termination of the reaction.

In PCR, a reagent in which a plurality of fluorescent dyes are mixed isoften used depending on an amplification target, and in this case, it isnecessary to install a plurality of fluorescence detection devices. Inparticular, in a reaction processing apparatus that detects fluorescencefrom a sample while moving the sample in a channel formed inside aplate-like reaction processing vessel, in order to detect fluorescencefrom a sample passing through a single channel whose cross-sectionalarea is, for example, 2 mm² or less, it is necessary to arrange aplurality of fluorescence detection devices in the extending directionof the channel.

For example, when amplifying O-157 by PCR, VT1 and VT2 are measured atthe same time . For example, a test kit (FIK-362) by Toyobo Co., Ltd.,uses ROX (a fluorescent dye that is excited by irradiation withsubstantially green light and emits substantially red fluorescence, andhereinafter, such a characteristic of fluorescence is referred to as“green excitation/red fluorescence”) and Cy5 (red excitation/infraredfluorescence). In this case, two fluorescence detection devices arenecessary.

When detecting norovirus, G1 and G2 are to be measured simultaneously.For example, a test kit (RR255A) by Takara Bio Inc., and a test kit(FIK-253) by Toyobo Co., Ltd., both use FAM (blue excitation/greenfluorescence), ROX (green excitation/red fluorescence), and Cy5 (redexcitation/infrared fluorescence) as fluorescent dyes. In this case,three fluorescence detection devices are necessary.

When fluorescence detection is performed on a sample that passes througha channel using a plurality of fluorescence detection devices asdescribed above, interference may occur between the fluorescencedetection devices. An explanation will be given using examples in thefollowing.

When FAM and ROX are used while being added to a sample at the same timeas fluorescent dyes, the wavelength range of light corresponding to thesubstantially green color of excitation light radiated to excite the ROXand the wavelength range of light corresponding to the substantiallygreen color of excitation light emitted from the FAM may partiallyoverlap. In that case, when a part of the excitation light radiated toexcite the ROX enters a photodetector such as a photoelectric conversionelement for detecting fluorescence emitted from the FAM, the part of theexcitation light becomes noise, and highly sensitive measurement may notbe able to be performed. Normally, the amount of excitation light isseveral tens of μW, while the amount of fluorescence to be detected ison the order of several pW or less. This is because fluorescencedetection devices are configured to detect such a weak amount offluorescence and even a small part of excitation light that reaches thephotodetector appears as large noise.

When ROX and Cy5 are used while being added to a sample at the same timeas fluorescent dyes, the wavelength range of substantially red light ofexcitation light radiated to excite the Cy5 and the wavelength range oflight corresponding to the substantially red color of fluorescenceemitted from the ROX may partially overlap . In that case also, when apart of the excitation light radiated to excite the Cy5 enters aphotodetector for detecting fluorescence emitted from the ROX, the partof the excitation light becomes noise, and highly sensitive fluorescencemeasurement may not be able to be performed.

In this background, a purpose of the present invention is to provide atechnology capable of suppressing interference between fluorescencedetection devices in a reaction processing apparatus provided with aplurality of fluorescence detection devices.

A reaction processing apparatus according to one embodiment of thepresent invention includes: a reaction processing vessel in which achannel where a sample moves is formed; a first fluorescence detectiondevice that irradiates a sample inside a first fluorescence detectionregion set in the channel with first excitation light and also detectsfirst fluorescence produced from the sample by the irradiation with thefirst excitation light; and a second fluorescence detection device thatirradiates a sample inside a second fluorescence detection region set inthe channel with second excitation light and also detects secondfluorescence produced from the sample by the irradiation with the secondexcitation light. The wavelength range of the first fluorescence and thewavelength range of the second excitation light overlap with each otherat least partially. The first excitation light and the second excitationlight flash at a predetermined duty ratio, and given that the duty ratioof the flashing of the first excitation light and the flashing of thesecond excitation light is d, the phase difference between the flashingof the first excitation light and the flashing of the second excitationlight is set within a range of 2π(p_(m)−Δp_(m)) (rad) to2π(p_(m)+Δp_(m)) (rad) or within a range of 2π[(1−p_(m))−Δp_(m)] (rad)to 2π[(1−p_(m))+Δp_(m)] (rad), where p_(m) =d−d² and Δp_(m)=0.01*p_(m).

Another embodiment of the present invention also relates to a reactionprocessing apparatus. This apparatus includes: a reaction processingvessel in which a channel where a sample moves is formed; a firstfluorescence detection device that irradiates a sample inside a firstfluorescence detection region set in the channel with first excitationlight and also detects first fluorescence produced from the sample bythe irradiation with the first excitation light; and a secondfluorescence detection device that irradiates a sample inside a secondfluorescence detection region set in the channel with second excitationlight and also detects second fluorescence produced from the sample bythe irradiation with the second excitation light. The wavelength rangeof the first fluorescence and the wavelength range of the secondexcitation light overlap with each other at least partially, and thefirst excitation light and the second excitation light flash at apredetermined duty ratio. Given that the duty ratio of the flashing ofthe first excitation light and the flashing of the second excitationlight is d, the phase difference between the flashing of the firstexcitation light and the flashing of the second excitation light is setwithin a range of 2π(p_(m)−Δp_(m)) (rad) to 2π(p_(m)+Δp_(m)) (rad) orwithin a range of 2π[(1−p_(m))−Δp_(m)] (rad) to 2π[(1−p_(m))+Δp_(m)](rad), where p_(m)=d−d² and Δp_(m)=(d−d²)/[k*(N_(o)′)/V¹ ₀], N₀ ′represents noise of a signal output of the first fluorescence detectiondevice when the phase difference between the flashing of the firstexcitation light and the flashing of the second excitation light is 0rad, V¹ ₀ represents a signal output of the first fluorescence detectiondevice when the second fluorescence detection device is not operating,and k is 20.

In the above embodiment, k may be 100/3.

Alternatively, k may be 100.

The first fluorescence detection device may include a first optical headthat emits the first excitation light and receives the firstfluorescence. The second fluorescence detection device may include asecond optical head that emits the second excitation light and receivesthe second fluorescence. When the respective numerical apertures of thefirst optical head and the second optical head are in a range of 0.07 to0.23, the distance between the center of the first fluorescencedetection region and the center of the second fluorescence detectionregion may be set to 4 mm or more.

The channel may include a first temperature region maintained at a firsttemperature, a second temperature region maintained at a secondtemperature higher than the first temperature, and a connection regionconnecting the first temperature region and the second temperatureregion. The movement of a sample inside the channel may be controlledbased on a fluorescence signal detected by the first fluorescencedetection device. The first fluorescence detection region may be set ata substantially intermediate point of the connection region.

The first fluorescence detection device may emit blue light as the firstexcitation light and detect green light as the first fluorescence. Thesecond fluorescence detection device may emit green light as the secondexcitation light and detect red light as the second fluorescence.

The reaction processing apparatus may further include: a thirdfluorescence detection device that irradiates a sample inside a thirdfluorescence detection region set in the channel with third excitationlight and also detects third fluorescence produced from the sample bythe irradiation with the third excitation light. The third fluorescencedetection device may emit red light as the third excitation light anddetect infrared light as the third fluorescence.

A first optical head of the first fluorescence detection device may bearranged in the center, and a second optical head of the secondfluorescence detection device and a third optical head of the thirdfluorescence detection device may be arranged on the respective sides ofthe first optical head.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements are numbered alike in severalFigs., in which:

FIGS. 1A and 1B are diagrams for explaining a reaction processing vesselusable in a reaction processing apparatus according to an embodiment ofthe present invention;

FIG. 2 is a schematic diagram for explaining the reaction processingapparatus according to the embodiment of the present invention;

FIG. 3 is a diagram for explaining the configuration of a fluorescencedetection device;

FIG. 4 is a diagram showing a state where a first optical head of afirst fluorescence detection device and a second optical head of asecond fluorescence detection device are arranged;

FIG. 5 is a diagram for explaining the circuit configuration of alock-in amplifier that processes a fluorescence signal from afluorescence detector;

FIG. 6 is a diagram showing the measurement result of a first signaloutput according to the first fluorescence detection device when thephase difference between a first modulation signal and a secondmodulation signal is changed;

FIG. 7 is a diagram showing the relationship between a signal output anda phase difference based on a fluorescence signal from a FAM aqueoussolution;

FIG. 8 is a diagram showing the relationship between noise and a phasedifference when the respective duty ratios of the first modulationsignal and the second modulation signal are both 50%;

FIG. 9 is a diagram showing the relationship between noise and a phasedifference when the respective duty ratios of the first modulationsignal and the second modulation signal are both 30%;

FIG. 10 is a diagram showing the relationship between noise and a phasedifference when the respective duty ratios of the first modulationsignal and the second modulation signal are both 40%;

FIGS. 11A, 11B, 11C and 11D are diagrams for explaining the operation ofthe lock-in amplifier when one of the two fluorescence detection devicesis stopped;

FIGS. 12A, 12B, 12C, 12D, 12E and 12F are diagrams for explaining theoperation of the lock-in amplifier when both of the two fluorescencedetection devices are operated;

FIG. 13 is a diagram for explaining how to determine an allowable rangefor a phase difference corresponding to the minimum value of a signaloutput of noise;

FIG. 14 is a diagram showing a relationship between a signal output fromthe first fluorescence detection device and time when the secondfluorescence detection device is stopped;

FIG. 15 is a diagram showing a relationship between a signal output fromthe first fluorescence detection device and time when the secondfluorescence detection device is operated;

FIG. 16 is a diagram for explaining an exemplary embodiment of thepresent invention;

FIG. 17 is a diagram showing a fluorescence signal output from the firstfluorescence detection device when an inter-fluorescent point distanceis set to 4 mm in the first exemplary embodiment;

FIG. 18 is a diagram showing a PCR amplification result in the firstexemplary embodiment;

FIG. 19 is a diagram showing a fluorescence signal output from the firstfluorescence detection device in a comparative example;

FIG. 20 is a diagram showing a PCR amplification result in thecomparative example; and

FIG. 21 is a diagram for explaining a reaction processing apparatusaccording to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An explanation will be given in the following regarding a reactionprocessing apparatus according to an embodiment of the presentinvention. The same or equivalent constituting elements, members, andprocesses illustrated in each drawing shall be denoted by the samereference numerals, and duplicative explanations will be omittedappropriately. Further, the embodiments do not limit the invention andare shown for illustrative purposes, and not all the features describedin the embodiments and combinations thereof are necessarily essential tothe invention.

FIGS. 1A and 1B are diagrams for explaining a reaction processing vessel10 usable in a reaction processing apparatus according to an embodimentof the present invention. FIG. 1A is a plan view of the reactionprocessing vessel 10, and FIG. 1B is a front view of the reactionprocessing vessel 10.

As shown in FIGS. 1A and 1B, the reaction processing vessel 10 comprisesa substrate 14 and a channel sealing film 16.

The substrate 14 is preferably formed of a material that is stable undertemperature changes and is resistant to a sample solution that is used.Further, the substrate 14 is preferably formed of a material that hasgood moldability, a good transparency and barrier property, and a lowself-fluorescence property. As such a material, an inorganic materialsuch as glass, silicon (Si), or the like, a resin such as acrylic,polypropylene, polyester, silicone, or the like, and particularlycycloolefin are preferred. An example of the dimensions of the substrate14 includes a long side of 75 mm, a short side of 25 mm, and a thicknessof 4 mm.

A groove-like channel 12 is formed on the lower surface 14 a of thesubstrate 14, and this channel 12 is sealed by the channel sealing film16. An example of the dimensions of the channel 12 formed on the lowersurface 14 a of the substrate 14 includes a width of 0.7 mm and a depthof 0.7 mm. A first communication port 17, which communicates with theoutside, is formed at the position of one end of the channel 12 in thesubstrate 14. A second communication port 18 is formed at the positionof the other end of the channel 12 in the substrate 14. The pair, thefirst communication port 17 and the second communication port 18, formedon the respective ends of the channel 12 is formed so as to be exposedon the upper surface 14 b of the substrate 14. Such a substrate can beproduced by injection molding or cutting work with an NC processingmachine or the like.

As shown in FIG. 1B, on the lower surface 14 a of the substrate 14, thechannel sealing film 16 is attached. In the reaction processing vessel10 according to the embodiment, most of the channel 12 is formed in theshape of a groove exposed on the lower surface 14 a of the substrate 14.This is for allowing for easy molding by injection molding using a metalmold or the like. In order to seal this groove so as to make use of thegroove as a channel, the channel sealing film 16 is attached on thelower surface 14 a of the substrate 14.

The channel sealing film 16 may be sticky and/or adhesive on one of themain surfaces thereof or may have a functional layer that exhibitsstickiness and/or adhesiveness through pressing, energy irradiation withultraviolet rays or the like, heating, etc., formed on one of the mainsurfaces. Thus, the channel sealing film 16 has a function of beingeasily able to become integral with the lower surface 14 a of thesubstrate 14 while being in close contact with the lower surface 14 a.The channel sealing film 16 is desirably formed of a material, includingan adhesive, that has a low self-fluorescence property. In this respect,a transparent film made of a resin such as cycloolefin, polyester,polypropylene, polyethylene or acrylic is suitable but is not limitedthereto. Further, the channel sealing film 16 may be formed of aplate-like glass or resin. Since rigidity can be expected in this case,the channel sealing film 16 is useful for preventing warpage anddeformation of the reaction processing vessel 10.

The channel 12 is provided with a reaction region where the control oftemperatures of a plurality of levels is possible by a reactionprocessing apparatus described later. A thermal cycle can be applied toa sample by moving the sample such that the sample continuouslyreciprocates in the reaction region where the temperatures of aplurality of levels are maintained.

The reaction region of the channel 12 shown in FIGS. 1A and 1B includesa serpiginous shape channel where a turn is continuously made bycombining curved portions and straight portions. When the reactionprocessing vessel 10 is mounted on a reaction processing apparatusdescribed later, the right side of the channel 12 in the figures isexpected to become a region of a relatively high temperature (about 95°C.) (hereinafter referred to as “high temperature region”), and the leftside of the channel 12 is expected to become a region of a lowertemperature (about 60° C.) (hereinafter referred to as “low temperatureregion”). Further, the reaction region of the channel 12 includes aconnection region for connecting the high temperature region and the lowtemperature region therebetween. This connection region may be a linearchannel.

When the high temperature region and the low temperature region areserpiginous shape channels as in the present embodiment, the effectivearea of a heater or the like constituting a temperature control meansdescribed later can be effectively used, and there are advantages thattemperature variance in the reaction region is easily reduced and thatthe substantial size of the reaction processing vessel can be reduced,allowing the reaction processing apparatus to be made small.

The sample subjected to a thermal cycle is introduced into the channel12 through either one of the first communication port 17 and the secondcommunication port 18. The method for the introduction is not limited tothis. Alternatively, for example, an appropriate amount of the samplemay be directly introduced through the communication port using apipette, a dropper, a syringe, or the like . Alternatively, a method ofintroduction may be used that is performed while preventingcontamination via a cone-shaped needle chip, in which a filter made ofporous PTFE or polyethylene is incorporated. In general, many types ofsuch needle chips are sold and can be obtained easily, and the needlechips can be used while being attached to the tip of a pipette, adropper, a syringe, or the like. Furthermore, the sample may be moved toa predetermined position in the channel by discharging and introducingthe sample by a pipette, a dropper, a syringe, or the like and thenfurther pushing the sample through pressurization.

The sample includes, for example, those obtained by adding a fluorescentdye, a thermostable enzyme and four types of deoxyribonucleosidetriphosphates (dATP, dCTP, dGTP, dTTP) as PCR reagents to a mixturecontaining one or more types of DNA. Further, a primer that specificallyreacts with the DNA subjected to reaction processing, and in some cases,a fluorescent probe such as TaqMan (TaqMan is a registered trademark ofRoche Diagnostics Gesellschaft mit beschrankter Haftung) are mixed.Commercially available real-time PCR reagent kits and the like can bealso used.

FIG. 2 is a schematic diagram for explaining a reaction processingapparatus 30 according to the embodiment of the present invention.

The reaction processing apparatus 30 according to the embodiment isprovided with a reaction processing vessel placing portion (not shown)on which the reaction processing vessel 10 is placed, a temperaturecontrol system 32, and a CPU 36. As shown in FIG. 2, relative to thereaction processing vessel 10 placed on the reaction processing vesselplacing portion, the temperature control system 32 is configured so asto be able to accurately maintain and control the temperature of theright side region of the channel 12 of the reaction processing vessel 10in the figure to be about 95° C. (high temperature range) and thetemperature of the left side region thereof in the figure to be about60° C. (low temperature range).

The temperature control system 32 is for maintaining the temperature ofeach temperature region of the reaction region and is specificallyprovided with a high temperature heater 60 for heating the hightemperature region of the channel 12, a low temperature heater 62 forheating the low temperature region of the channel 12, a temperaturesensor (not shown) such as, for example, a thermocouple or the like formeasuring the actual temperature of each temperature region, a hightemperature heater driver 33 for controlling the temperature of the hightemperature heater 60, and a low temperature heater driver 35 forcontrolling the temperature of the low temperature heater 62.Information on the actual temperature measured by the temperature sensoris sent to the CPU 36. Based on the information on the actualtemperature of each temperature region, the CPU 36 controls each heaterdriver such that the temperature of each heater becomes a predeterminedtemperature. Each heater may be, for example, a resistance heatingelement, a Peltier element, or the like. The temperature control system32 may be further provided with other components for improving thetemperature controllability of each temperature region.

The reaction processing apparatus 30 according to the present embodimentis further provided with a liquid feeding system 37 for moving, insidethe channel 12, the sample 20 introduced into the channel 12 of thereaction processing vessel 10. The liquid feeding system 37 is providedwith a first pump 39, a second pump 40, a first pump driver 41 fordriving the first pump 39, a second pump driver 42 for driving thesecond pump 40, a first tube 43, and a second tube 44.

One end of the first tube 43 is connected to the first communicationport 17 of the reaction processing vessel 10. A packing material 45 or aseal for securing airtightness is preferably arranged at the junction ofthe first communication port 17 and the end of the first tube 43. Theother end of the first tube 43 is connected to the output of the firstpump 39. In the same way, one end of the second tube 44 is connected tothe second communication port 18 of the reaction processing vessel 10. Apacking material 46 or a seal for securing airtightness is preferablyarranged at the junction of the second communication port 18 and the endof the second tube 44. The other end of the second tube 44 is connectedto the output of the second pump 40.

The first pump 39 and the second pump 40 may be, for example, microblower pumps each comprising a diaphragm pump. As the first pump 39 andthe second pump 40, for example, micro blower pumps (MZB1001 T02 model)manufactured by Murata Manufacturing Co., Ltd., or the like can be used.While this micro blower pump can increase the pressure on a secondaryside to be higher than a primary side during operation, the pressure onthe primary side and the pressure on the secondary side become equal atthe moment when the pump is stopped or when the pump is stopped.

The CPU 36 controls the air supply and pressurization from the firstpump 39 and the second pump 40 via the first pump driver 41 and thesecond pump driver 42. The air supply and pressurization from the firstpump 39 and the second pump 40 act on the sample 20 inside the channelthrough the first communication port 17 and the second communicationport 18 and becomes a propulsive force to move the sample 20. Morespecifically, by alternately operating the first pump 39 and the secondpump 40, the pressure applied to either end surface of the sample 20becomes larger than the pressure applied to the other end, and apropulsive force relating to the movement of the sample 20 can thus beobtained. By alternately operating the first pump 39 and the second pump40, the sample 20 can be moved in a reciprocating manner in the channelso as to pass through each temperature region of the channel 12 of thereaction processing vessel 10. As a result, a thermal cycle can beapplied to the sample 20. More specifically, target DNA in the sample 20is selectively amplified by repeatedly applying a step of denaturationin the high temperature region and a step of annealing and elongation inthe low temperature region. In other words, the high temperature regioncan be considered to be a denaturation temperature region, and the lowtemperature region can be considered to be an annealing and elongationtemperature region. The time for staying in each temperature region canbe appropriately set by changing the time during which the sample 20stops at a predetermined position in each temperature region.

The reaction processing apparatus 30 according to the embodiment isfurther provided with a first fluorescence detection device 50 and asecond fluorescence detection device 54. As described above, apredetermined fluorescent dye is added to the sample 20. Since theintensity of a fluorescence signal emitted from the sample 20 increasesas the amplification of the DNA proceeds, the intensity value of thefluorescence signal can be used as an index serving as a decisionmaterial for the progress of the PCR or the termination of the reaction.

As the first fluorescence detection device 50 and the secondfluorescence detection device 54, optical fiber-type fluorescencedetectors FLE-510 manufactured by Nippon Sheet Glass Co., Ltd., can beused, which are very compact optical systems that allow for rapidmeasurement and the detection of fluorescence regardless of whether theplace is a lighted place or a dark place. These optical fiber-typefluorescence detectors allow the wavelength characteristic of theexcitation light/fluorescence to be tuned such that the wavelengthcharacteristic is suitable for the characteristic of fluorescenceemitted from the sample 20 and thus allow an optimum optical anddetection system for a sample having various characteristics to beprovided. Further, the optical fiber-type fluorescence detectors aresuitable for detecting fluorescence from a sample existing in a small ornarrow region such as a channel because of the small diameter of a rayof light brought by the optical fiber-type fluorescence detectors.

The first fluorescence detection device 50 is provided with a firstoptical head 51, a first fluorescence detection excitation lightsource/detector module 52, and an optical fiber F12 connecting the firstoptical head 51 and the first fluorescence detection excitation lightsource/detector module 52. In the same manner, the second fluorescencedetection device 54 is provided with a second optical head 55, a secondfluorescence detection excitation light source/detector module 56, andan optical fiber F22 connecting the second optical head 55 and thesecond fluorescence detection excitation light source/detector module56.

The first fluorescence detection excitation light source/detector module52 and the second fluorescence detection excitation lightsource/detector module 56 each include a light source for excitationlight, a wavelength multiplexer/demultiplexer, a fluorescence detector,and a driver or the like for controlling these. Each of the firstoptical head 51 and the second optical head 55 is formed of an opticalsystem such as a lens and has a function of directionally irradiatingthe sample with excitation light and collecting fluorescence emittedfrom the sample. Fluorescence condensed by the first optical head 51 andfluorescence collected by the second optical head 55 are separated fromexcitation light by the respective wavelengthmultiplexers/demultiplexers in the first fluorescence detectionexcitation light source/detectormodule 52 and the second fluorescencedetection excitation light source/detector module 56 via the opticalfibers F12 and F22, respectively, and are converted into electricsignals by the respective fluorescence detectors. The details of theconfiguration of the fluorescence detection devices will be describedlater.

In the reaction processing apparatus 30 according to the presentembodiment, the first optical head 51 is arranged such that fluorescencefrom the sample 20 passing through a partial region 12 a (referred to as“first fluorescence detection region 12 a”) inside the connection regionconnecting the high temperature region and the low temperature regioncan be detected. Further, the second optical head 55 is arranged suchthat fluorescence can be detected from the sample 20 passing throughanother partial region 12 b (referred to as “second fluorescencedetection region 12 b”) inside the connection region. Since the reactionprogresses while the sample 20 is repeatedly moved in a reciprocatingmanner in the channel such that predetermined DNA contained in thesample 20 is amplified, by monitoring a change in the amount of detectedfluorescence, the progress of the DNA amplification can be learned inreal time.

FIG. 3 is a diagram for explaining the configuration of a fluorescencedetection device. The configuration of the first fluorescence detectiondevice 50 is explained in FIG. 3. However, the second fluorescencedetection device 54 also has the same configuration except that thecenter wavelength of the bandpass filter is different.

As shown in FIG. 3, the first fluorescence detection device 50 isprovided with a first optical head 51, a first fluorescence detectionexcitation light source/detector module 52, and an optical fiber F12connecting the first optical head 51 and the first fluorescencedetection excitation light source/detector module 52. The firstfluorescence detection excitation light source/detector module 52includes a first excitation light source 64, a first wavelengthmultiplexer/demultiplexer 65, and a first fluorescence detector 66.These functional elements are connected by optical fibers, andexcitation light and fluorescence propagate inside the optical fibers.

A bandpass filter A1 is arranged near the first excitation light source64 such that excitation light emitted from the first excitation lightsource 64 is transmitted. The first wavelength multiplexer/demultiplexer65 has a bandpass filter B1. A bandpass filter C1 is arranged near thefirst fluorescence detector 66 such that fluorescence incident on thefirst fluorescence detector 66 is transmitted. The wavelengthcharacteristics of these bandpass filters are designed according to thewavelength characteristics related to excitation/fluorescence of afluorescent dye such as FAM. Each of the bandpass filters has aspectroscopic function of transmitting light in a specific wavelengthrange with high efficiency (for example, transmittance of 75% or more)and reflecting light of other wavelengths with high efficiency (forexample, reflectance of 75% or more, and desirably 85% or more).

In the present embodiment, the first fluorescence detection device 50 isformed to be able to detect fluorescence from a sample containing FAM asa fluorescent dye.

The first excitation light source 64 is not particularly limited as longas the first excitation light source 64 is a light source that candisperse light of a target wavelength later, and for example, LD, LED,white light source, or the like can be used. Excitation light emittedfrom the first excitation light source 64 is dispersed by the bandpassfilter A1, and only light having a wavelength in a predetermined rangewith a center wavelength of about 470 nm (hereinafter, referred to as“excitation light OE1”) propagates inside the optical fiber F11.

The excitation light OE1 enters the first wavelengthmultiplexer/demultiplexer 65, is collimated by the lens L1, and thenreaches the bandpass filter B1. Since the bandpass filter B1 is designedto reflect the excitation light OE1, the excitation light OE1 iscondensed again by the lens L1 and enters the optical fiber F12. Theexcitation light OE1 propagates inside the optical fiber F12 and reachesthe first optical head 51. An objective lens OB1 is provided inside thefirst optical head 51, and the excitation light OE1 is applied to thesample 20 as excitation light at a predetermined working distance.

When the excitation light OE1 is applied to the sample 20, a fluorescentdye inside the sample 20 is excited, and fluorescence light OF1 isemitted from the sample 20. The fluorescence OF1 is condensed by theobjective lens OB1 of the first optical head 51, enters the opticalfiber F12, and propagates inside the optical fiber F12. The fluorescenceOF1 enters the first wavelength multiplexer/demultiplexer 65, iscollimated by the lens L1, and then reaches the bandpass filter B1.

In general, the wavelength of fluorescence generated by irradiation withexcitation light is longer than the wavelength of excitation light. Thatis, given that the center wavelength of excitation light is λe and thatthe center wavelength of fluorescence is λf, λe<λf is satisfied.Therefore, in order to guide only the fluorescence OF1 to the firstfluorescence detector 66, a bandpass filter having a spectralcharacteristic of reflecting light of a wavelength of λe andtransmitting light of a wavelength of λf is used as the bandpass filterB1. The bandpass filter B1 is designed to transmit, in the fluorescenceOF1, light having a wavelength in a range that does not overlap with thewavelength of the excitation light OE1. The fluorescence OF1 that haspassed through the bandpass filter B1 is condensed by the lens L2 andenters the optical fiber F13. Further, since the bandpass filter B1 hasa function of reflecting excitation light and transmitting fluorescence,an edge filter capable of reflecting light in a wavelength rangeincluding λe and transmitting light in a wavelength range including λfin accordance with the respective center wavelengths thereof can be usedinstead of a bandpass filter.

The fluorescence OF1 propagating inside the optical fiber F13 reachesthe first fluorescence detector 66. In order to precisely adjust thewavelength range, the fluorescence OF1 may pass through the bandpassfilter C1 before entering the first fluorescence detector 66. Only lighthaving a wavelength within a predetermined range with a centerwavelength of about 530 nm that has passed through the bandpass filtersB1 and C1 enters the first fluorescence detector 66. The firstfluorescence detector 66 is a photoelectric conversion element such asPD, APD, or photomultiplier. A signal converted into an electricalsignal by the first fluorescence detector 66 is subjected to a signalprocess described later.

In the first fluorescence detection device 50 shown in FIG. 3, eachelement may include a lens for efficiently transmitting or couplinglight or for improving the utilization efficiency of a bandpass filter.As the lens, a gradient index lens, a ball lens, an aspherical lens, orthe like can be used. Further, in the first fluorescence detectiondevice 50 shown in FIG. 3, single mode fibers or multimode fibers may beused for the optical fibers F11, F12, and F13.

The first fluorescence detection device 50 formed as described aboveirradiates the sample with light having a center wavelength of 470 nmand a wavelength range of about 450 to 490 nm as first excitation lightOE1, and detects first fluorescence OF1 having a center wavelength of530 nm and a wavelength range of about 510 to 550 nm emitted by thesample. A person skilled in the art should appreciate that thecharacteristics relating to wavelengths are determined by thecombination of the transmission characteristics or the reflectioncharacteristics of each bandpass filter as described above and thatthose characteristics can be changed or customized.

On the other hand, in the present embodiment, the second fluorescencedetection device 54 is formed to be able to detect fluorescence from asample containing ROX as a fluorescent dye. The second fluorescencedetection device 54 irradiates the sample with light having a centerwavelength of 530 nm and a wavelength range of about 510 to 550 nm assecond excitation light OE2, and detects second fluorescence OF2 havinga center wavelength of 610 nm and a wavelength range of about 580 to 640nm.

FIG. 4 shows a state where the first optical head 51 of the firstfluorescence detection device 50 and the second optical head 55 of thesecond fluorescence detection device 54 are arranged. The optical head51 is arranged so as to be able to detect fluorescence from the sample20 passing through the first fluorescence detection region 12 a of thechannel 12. The second optical head 55 is arranged so as to be able todetect fluorescence from the sample 20 passing through the secondfluorescence detection region 12 b of the channel 12. Further, eitherone of the first optical head 51 of the first fluorescence detectiondevice 50 and the second optical head 55 of the second fluorescencedetection device 54 may be arranged near the middle of the connectionregion or the midway between the low temperature region and the hightemperature region.

As shown in FIG. 4, the first optical head 51 allows the firstexcitation light OE1 propagating inside the optical fiber F12 to becondensed by the objective lens OB1, irradiates the sample 20 passingthrough the first fluorescence detection region 12 a with the resultingfirst excitation light OE1, and allows the first fluorescence OF1generated from the sample 20 to be condensed by the objective lens OB1and enter the optical fiber F12. In the same manner, the second opticalhead 55 allows the second excitation light OE2 propagating inside theoptical fiber F22 to be condensed by the objective lens OB2, irradiatesthe sample 20 passing through the second fluorescence detection region12 b with the resulting second excitation light OE2, and allows thesecond fluorescence OF2 generated from the sample 20 to be condensed bythe objective lens OB2 and enter the optical fiber F22.

The respective diameters of the first optical head 51 and the secondoptical head 55 are, for example, 1 to 4 mm, and the first optical head51 and the second optical head 55 are arranged at an arbitrary intervallarger than that. The distance between the center of the firstfluorescence detection region 12 a irradiated with the first excitationlight OE1 from the first optical head 51 and the center of the secondfluorescence detection region 12 b irradiated with the second excitationlight OE2 from the second optical head 55 is referred to as“inter-fluorescent point distance tp”.

As the objective lenses OB1 and OB2, lenses or a lens group havingpositive power, for example, Selfoc (registered trademark) microlenses,which are gradient index lenses, can be used. As the objective lensesOB1 and OB2, for example, those having a diameter of 1.8 mm, a numericalaperture (NA) of 0.23, and a WD of 1 mm to 3 mm can be used.

In the present embodiment, the first excitation light source of thefirst fluorescence detection device 50 is modulated by the firstmodulation signal and emits flashing light. In the same manner, thesecond excitation light source of the second fluorescence detectiondevice 54 is modulated by the second modulation signal and emitsflashing light.

FIG. 5 is a diagram for explaining the circuit configuration of alock-in amplifier that processes a fluorescence signal from afluorescence detector.

In the present embodiment, the first fluorescence signal from the firstfluorescence detector 66 of the first fluorescence detection device 50is processed by a first lock-in amplifier 68. The first lock-inamplifier 68 includes an IV amplifier 70, a high pass filter 80, aninverting/non-inverting amplifier 81, and a low pass filter 82. Thefirst fluorescence signal output from the first fluorescence detector 66is appropriately amplified by the IV amplifier 70, and then the DCcomponent is removed by the high pass filter (HPF) 80. This signal isfurther synchronously detected by the inverting/non-inverting amplifier81 with the first modulation signal and converted into a direct current.The low pass filter (LPF) 82 removes noise from the signal convertedinto a direct current, and a first signal output according to the firstfluorescence detection device 50 can be finally obtained.

The second fluorescence signal from the second fluorescence detector 67of the second fluorescence detection device 54 is processed by a secondlock-in amplifier 69. The configuration of the second lock-in amplifier69 is the same as that of the first lock-in amplifier 68. By processingthe second fluorescence signal from the second fluorescence detector 67using the second lock-in amplifier 69, a second signal output accordingto the second fluorescence detection device 54 can be finally obtained.

In the present embodiment, the first optical head 51 and the secondoptical head 55 are arranged side by side in order to detect the sample20 passing through a single channel 12. As described above, the firstfluorescence detection device 50 emits the first excitation light OE1having a center wavelength of 470 nm and a wavelength range of about 450to 490 nm, and detects first fluorescence OF1 having a center wavelengthof 530 nm and a wavelength range of about 510 to 550 nm. The secondfluorescence detection device 54 emits the second excitation light OE2having a center wavelength of 530 nm and a wavelength range of about 510to 550 nm, and detects second excitation light OE2 having a centerwavelength of 610 nm and a wavelength range of about 580 to 640 nm.Therefore, the wavelength range of the second excitation light OE2(about 510 to 550 nm) and the wavelength range of the first fluorescenceOF1 (about 510 to 550 nm) overlap. In this case, when a part of thesecond excitation light OE2 emitted from the second optical head 55 isdetected by the first optical head 51, the second excitation light OE2may not be removed by the post-stage bandpass filters B1 and C1 of thefirst optical head 51 and may reach the first fluorescence detector 66.The second excitation light OE2 is noise in the first fluorescencedetector 66, and the first fluorescence OF1, which should be essentiallydetected, may not be able to be detected.

When the first optical head 51 and the second optical head 55 arearranged so as to be sufficiently separated from each other, such aproblem does not arise. However, the size of the reaction processingapparatus 30 becomes large in this case. In order to solve such acontradictory problem, the present inventors diligently studied andinvestigated what kind of influence the fluorescence detection wouldhave when the two optical heads are arranged side by side.

The present inventors actually examined what kind of influence wascaused on the detection of fluorescence from a sample by the phasedifference between a first modulation signal (first excitation lightsource modulation signal) according to the first fluorescence detectiondevice 50 and a second modulation signal (second excitation light sourcemodulation signal) according to the second fluorescence detection device54, in other words, the phase difference between flashing of the firstexcitation light and flashing of the second excitation light. Theexperimental conditions are shown below.

(1) As shown in FIG. 4, the first optical head 51 and the second opticalhead 55 were arranged side by side such that fluorescence from thesample 20 in the channel 12 could be condensed. The inter-fluorescentpoint distance tp, which is the distance between the center of the firstfluorescence detection region 12 a and the center of the secondfluorescence detection region 12 b, was set to 4.5 mm. (2) A firstmodulation signal having a first modulation frequency (110 Hz) wasgenerated by a pulse generator or the like, and first excitation lightfrom the first excitation light source was modulated using the firstmodulation signal. In the same manner, a second modulation signal havinga second modulation frequency (110 Hz) was generated, and secondexcitation light from the second excitation light source was modulatedusing the second modulation signal. The respective duty ratios of thefirst modulation signal and the second modulation signal were both 50%.(3) The phase difference Δφ between the modulation by the firstmodulation signal and the modulation by the second modulation signal waschanged, and a first signal output according to the first fluorescencedetection device 50 was measured. In this exemplary embodiment, athermal cycle was not applied since only the phase difference dependencywas detected for a fluorescence signal.

FIG. 6 shows the measurement result of a first signal output accordingto the first fluorescence detection device 50 when the phase differencebetween a first modulation signal and a second modulation signal ischanged. In FIG. 6, black circle plot shows the measurement result whena FAM aqueous solution was used as a sample (indicated as “FAM aqueoussolution”). A FAM aqueous solution (concentration of 30 nM) was putinside the channel 12 of the reaction processing vessel 10, and thephase difference Δφ between the first modulation signal and the secondmodulation signal was changed from 0° to 360°, a first signal outputaccording to the first fluorescence detection device 50 was measured.Also, in FIG. 6, a white circle plot shows the result (displayed as“blank”) of measuring the first signal output in a state where nothingwas put inside the channel 12 of the reaction processing vessel 10 (thatis, a blank state).

As can be seen from FIG. 6, in both the “FAM aqueous solution” and the“blank” cases, the first signal output also changes according to thechange in the phase difference Δφ, and the first signal output becomesmaximum when the phase difference Δφ is 0° and 360° (that is, there isno phase difference), and the first signal output becomes minimum whenthe phase difference Δφ is 180°.

The signal output based on a fluorescence signal emitted from the FAMaqueous solution as the sample is obtained by subtracting the value ofthe first signal output in the case of “blank” from the value of thefirst signal output in the case of “FAM aqueous solution” shown in FIG.6. By this calculation, the signal output based on the net fluorescencesignal from the FAM aqueous solution can be obtained. The relationshipbetween this signal output and the phase difference Δφ (°) is shown by ablack square plot (displayed as FAM aqueous solution (excluding blank))in FIG. 7.

Based on FIG. 7, it can be found that the signal intensity based on thenet fluorescence signal from the FAM aqueous solution varies dependingon the value of the phase difference Δφ between the first modulationsignal of the first excitation light source and the second modulationsignal of the second excitation light source. This means that the secondexcitation light has an influence on the fluorescence detection of thefirst fluorescence detection device 50 and that the degree of theinfluence differs depending on the phase difference Δφ.

Then, after stopping the second excitation light source, the respectiveintensities of the first signal outputs for the “blank” and the “FAMaqueous solution” were measured, and the difference between theintensities was calculated so as to obtain the signal intensity based onthe net fluorescence signal from the FAM aqueous solution. In this case,since the second excitation light source was stopped, there was noconcept of the phase difference Δφ, and the first signal output wasconstant (4.0). This value is based on the fluorescence signal from theFAM aqueous solution excluding the blank and is not affected by otherexcitation light/fluorescence detection systems. This value is shown bya solid line in FIG. 7 (displayed as “net signal s”).

The absolute value obtained by subtracting the value of the “net signals” from the value of the “FAM aqueous solution (excluding blank)”corresponds to noise. The relationship between this noise (N′) and thephase difference Δφ (°) is shown in FIG. 8. Based on FIG. 8, it can befound that, even in the presence of the second excitation lightaccording to the second fluorescence detection device 54, the noise ofthe fluorescence signal obtained through the first lock-in amplifier 68from the first fluorescence detector 66 according to the firstfluorescence detection device 50 is minimum when the phase difference Δφis 90° and when the phase difference Δφ is 270°.

FIG. 9 shows the relationship between the noise and the phase differencewhen the respective duty ratios of the first modulation signal and thesecond modulation signal are both 30%. FIG. 10 shows the relationshipbetween the noise and the phase difference when the respective dutyratios of the first modulation signal and the second modulation signalare both 40%. In both FIGS. 9 and 10, the inter-fluorescent pointdistance tp was set to 4.5 mm. As shown in FIG. 9, phase differences Δφat which noise N′ became minimum when the duty ratios were 30% wereabout 76° and about 284°. Further, as shown in FIG. 10, phasedifferences Δφ at which noise N′ became minimum when the duty ratioswere 40% were about 86° and about 274°.

From the above experimental results, it can be found that the optimumphase difference at which the noise N′ becomes minimum changes dependingon the difference in the respective duty ratios of the first modulationsignal and the second modulation signal. This can be expressed using amathematical expression, as can be derived from the followingconsideration.

FIGS. 11A, 11B, 11C and 11D are diagrams for explaining the operation ofa lock-in amplifier when one of the two fluorescence detection devicesis stopped. A case is now considered where, of the first fluorescencedetection device 50 and the second fluorescence detection device 54, thesecond fluorescence detection device 54 is stopped (without causing thesecond excitation light source to emit flashing light) and a signalreceived by the first fluorescence detector 66 of the first fluorescencedetection device 50 is processed by the first lock-in amplifier 68.Since the second fluorescence detection device 54 is stopped, the firstfluorescence signal to be detected by the first fluorescence detectiondevice 50 is not affected by the second excitation light of the secondfluorescence detection device 54.

In the first lock-in amplifier 68 shown in FIG. 5, the output after thepassing through the IV amplifier 70 is denoted as V¹ ₁, the output afterthe passing through the high pass filter 80 is denoted as V¹ ₂, theoutput after the passing through the inverting/non-inverting amplifier81 is denoted as V¹ _(4a), and the output after the passing through thelow pass filter 82 is denoted as V¹ ₄. In the explanation of lock-inamplifiers including the following explanation, output-related symbolsthat include V are arbitrary units according to voltage (Volt).

FIG. 11A shows the output V¹ ₁ after the passing through the IVamplifier. FIG. 11B shows the output V¹ ₂ after the passing through thehigh pass filter. FIG. 11C shows the output V¹ _(4a) after the passingthrough the inverting/non-inverting amplifier. FIG. 11D shows the outputV¹ ₄ after the passing through the low pass filter. In FIGS. 11A, 11B,11C and 11D, the horizontal axis represents the phase and the verticalaxis represents the signal output. A so-called one cycle is 360° or 2πrad. The arbitrary phase φ (°) shows a relationship of φ*π/180 (rad). Inconsideration of ease of calculation, the phase is mainly represented byrad (radian).

For simplicity, a case is considered where the output V¹ ₁ after thepassing through the IV amplifier is a rectangular signal as shown inFIG. 11A. V¹ ₁ is a rectangular signal having an output value of 1 inthe region of a phase corresponding to a section α and an output valueof 0 in the region of a phase corresponding to a section β in a singlecycle under a constant frequency. The duty ratio of this rectangularsignal is expressed by d=α/(α+β) (0<d<1) or d=α/2π. Although the dutyratio of the output V¹ ₁ after the passing through the IV amplifier isdescribed here, this duty ratio is the same as the duty ratio of thefirst excitation light emitted from the first excitation light source 64that is turned on/off under the same frequency.

When a rectangular signal as shown in FIG. 11A passes through the highpass filter 80, the direct current component is cut. Thus, an outputsignal as shown in FIG. 11B is obtained. When the signal shown in FIG.11B passes through the inverting/non-inverting amplifier 81, the sign ofan output signal belonging to the above region of a phase correspondingto the section β is inverted, and an output signal as shown in FIG. 11Cis therefore obtained. Further, when a signal as shown in FIG. 11Cpasses through the low pass filter 82, the alternating-current componentis cut. Thus, an output signal as shown in FIG. 11D is obtained. Theoutput value V¹ ₄ after the passing through the low pass filter can beexpressed by the following expression (1) using a duty ratio d.

$\begin{matrix}{V_{4}^{1} = {2*d*\left( {1 - d} \right)}} & (1)\end{matrix}$

FIGS. 12A, 12B, 12C, 12D, 12E and 12F are diagrams for explaining theoperation of the lock-in amplifier when both of the two fluorescencedetection devices are operated. A case is considered where the firstfluorescence detection device 50 and the second fluorescence detectiondevice 54 are operated and a signal received by the first fluorescencedetector 66 of the first fluorescence detection device 50 is processedby the first lock-in amplifier 68. Since the second fluorescencedetection device 54 is being operated, the first fluorescence signal tobe detected by the first fluorescence detection device 50 is affected bythe second excitation light of the second fluorescence detection device54.

FIG. 12A shows the output V¹ ₁ of the first lock-in amplifier 68 afterthe passing through the IV amplifier 70 when there is no influence ofthe second excitation light according to the second fluorescencedetection device 54. As in the same way as in FIG. 11A, a rectangularsignal is considered that has an output value of 1 in the region of aphase corresponding to the section α and an output value of 0 in theregion of a phase corresponding to the section β in a single cycle undera constant frequency and has the same duty ratio d as that in FIG. 11A.

FIG. 12B shows a signal after light derived from the second excitationlight according to the second fluorescence detection device 54 isreceived by the first fluorescence detector 66 and passes through the IVamplifier 70 of the first lock-in amplifier 68. This signal has anoutput value a (0<a<1) in the region of a phase corresponding to thesection α and an output value of 0 in the region of a phasecorresponding to the section β in a single cycle under the samefrequency as that for V¹ ₁. This signal has the same duty ratio d asthat for V¹ ₁. However, the signal derived from the second excitationlight is delayed by 2πp (rad) (p is a parameter, 0<p<1) from the outputsignal V¹ ₁ shown in FIG. 12A. There is a relationship of Δφ=360*pbetween the phase difference expressed by Δφ (°) and the phasedifference pressed by 2πp (rad).

FIG. 12C shows the output V¹ ₁ actually output from the IV amplifier 70.This is the sum of the output signal shown in FIG. 12A and the outputsignal shown in FIG. 12B.

FIG. 12D shows the output V¹ ₂ after the passing through the high passfilter 80. The bias associated with the cutting of the direct currentcomponent due to the passing through the high pass filter 80 is assumedto be (−x). In the area of a region enclosed by the output and thephase, the area of a region on the positive side and the area of aregion on the negative side are the same with 0 as the boundary.Therefore, the following expression (2) is satisfied.

$\begin{matrix}{{{{{From}\mspace{14mu}\left( {1 - x} \right)*p} + {\left( {1 + a - x} \right)*\left( {d - p} \right)} + {\left( {a - x} \right)*p} + {\left( {- x} \right)*\left\{ {1 - \left( {d + p} \right)} \right\}}} = 0},} & \; \\{x = {\left( {1 + a} \right)*d}} & (2)\end{matrix}$

FIG. 12E shows the output V¹ _(4a) after the passing through theinverting/non-inverting amplifier 81. FIG. 12F shows the output V¹ ₄after the passing through the low pass filter 82. When the signal shownin FIG. 12D passes through the inverting/non-inverting amplifier 81, thesign of an output signal belonging to the region of a phasecorresponding to the section β according to the first fluorescencedetection device is inverted, and an output signal as shown in FIG. 12Eis therefore obtained. Further, when a signal as shown in FIG. 12Epasses through the low pass filter 82, the alternating-current componentis cut. Thus, an output signal as shown in FIG. 12F is obtained.

When the output (that is, the first signal output) V¹ ₄ after thepassing through the low pass filter 82 is expressed in consideration ofthe relationship in the expression (2), the output is expressed in thefollowing expression (3).

$\begin{matrix}{V_{4}^{1} = {{{- 2}*\left( {1 + a} \right)*d^{2}} + {2*\left( {1 + a} \right)*d} - {2*a*p}}} & (3)\end{matrix}$

From the above consideration, in the first signal output, the amount ofoutput (the absolute value thereof) obtained by subtracting theexpression (1) from the expression (3) is superimposed on the firstsignal output as noise. Thus, the value of a noise component V¹ _(N) isexpressed by the following expression (4).

$\begin{matrix}{V_{N}^{1} = {{{- 2}*a*\left( {d^{2} - d + p} \right)}}} & (4)\end{matrix}$

In the expression (4), when d²−d+p=0 is satisfied, V¹ _(N) becomes theminimum (0), and the value pm of the parameter p at this time isexpressed by the following expression (5).

$\begin{matrix}{p_{m} = {d - d^{2}}} & (5)\end{matrix}$

From this expression (5), the p_(m) values when the duty ratio is 0.5(50%), 0.4 (40%), and 0.3 (30%) can be calculated to be 0.25, 0.24, and0.21, respectively. Further, the optimum phase differences that minimizethe noise component V¹ _(N) corresponding to these pm can be obtained tobe 0.5π rad, 0.48π rad, and 0.42π rad. Also, in the notation in degrees(°), Δφ_(m)=90.0°, Δφ_(m)=86.4°, and Δφ_(m)=75.6° can be obtained. Theseare almost the same as the above experimental results, and the validityof the experimental results is thus confirmed. Further, in comparisonwith the above experimental results, it can be understood that the noisecomponent V¹ _(N) is also minimum when the phase difference is2π(1−p_(m)) (rad) and Δφ_(m)=360(1−p_(m)) (°).

As described above, in the reaction processing apparatus 30 according tothe present embodiment, by setting the phase difference between flashingof the first excitation light emitted from the first optical head 51 andflashing of the second excitation light emitted from the second opticalhead 55 to be 2πp_(m) (rad) or 2π(1−p_(m)) (rad) using the pm set by theexpression (5) (notation in units of degrees (°) is 360p_(m) (°) or360(1−p_(m)) (°)), the interference between the first fluorescencedetection device 50 and the second fluorescence detection device 54 canbe suppressed.

FIG. 13 is a diagram for explaining how to determine an allowable rangeΔp_(m) in p_(m) corresponding to the minimum value of a signal output ofnoise N′, where N′ is the above-described noise notation V¹ _(N). FIG.13 shows the relationship between the signal output of noise N′ and thephase difference 2πp (rad).

Given that the noise N′ when the phase difference 2πp is 0 rad is N₀′,that the allowable value of the noise N′ is N_(m)′, and that the firstsignal output according to the first fluorescence detection device 50when the second fluorescence detection device 54 is not operating is V¹₀, the allowable range Δp_(m) in p_(m) of the parameter p is expressedby the following expression (6) in consideration of the above expression(5).

$\begin{matrix}{{\Delta\; p_{m}} = {{\left( N_{m}^{\prime} \right)*{\left( {d - d^{2}} \right)/\left( N_{0}^{\prime} \right)}} = {\left( {N_{m}^{\prime}/V_{0}^{1}} \right)*{\left( {d - d^{2}} \right)/\left\lbrack {\left( N_{0}^{\prime} \right)/V_{0}^{1}} \right\rbrack}}}} & (6)\end{matrix}$

Since the ratio of N_(m)′ to the first signal output V¹ ₀ according tothe first fluorescence detection device 50 when the second fluorescencedetection device 54 is not operating is required to be 0.05 (5%), theallowable range Δp_(m) is set to a value obtained by the followingexpression (7).

$\begin{matrix}{{\Delta\; p_{m}} = {\left( {d - d^{2}} \right)/\left\lbrack {20*{\left( N_{0}^{\prime} \right)/V_{0}^{1}}} \right\rbrack}} & (7)\end{matrix}$

For example, when V¹ ₀=4 is satisfied and N₀′ of about 50 is required,and when the duty of the fluorescence detection device is 0.4,p_(m)=0.24 and the phase difference 2πp_(m)=0.48π rad (86.4°) aresatisfied. From the expression (7), Δp_(m)=0.00096 is satisfied, and theallowable range of the phase difference is obtained to be 0.00192πrad(0.35°). Therefore, the appropriate range of the phase difference can be0.48π±0.00192π (rad) (86.4±0.35 (°)), and further can be 1.52π±0.00192π(rad) (273.6±0.35 (°).

Further, since the ratio of N_(m)′ to the first signal output V¹ ₀ ismore desirably 0.03 (3%), the allowable range Δp_(m) is set to a valueobtained by the following expression (8). In the same way, given that V¹₀=4, N₀′=50, and d=0.4 are satisfied, Δp_(m)=0.00058 is satisfied, andthe allowable range of the phase difference is obtained to be 0.00116πrad (0.21°). Therefore, the appropriate range of the phase differencecan be 0.48π±0.00116π (rad) (86.4±0.21 (°), and further can be1.52π±0.00116π (rad) (273.6±0.21 (°)).

$\begin{matrix}{{\Delta\; p_{m}} = {3*{\left( {d - d^{2}} \right)/\left\lbrack {100*{\left( N_{0}^{\prime} \right)/V^{1}}0} \right\rbrack}}} & (8)\end{matrix}$

In addition, since the ratio of N_(m)′ to the first signal output V¹ ₀is further desirably 0.01 (1%), the allowable range Δp_(m) is set to avalue obtained by the following expression (9). In the same way, giventhat V¹ ₀=4, N₀′=50, and d=0.4 are satisfied, Δp_(m)=0.00019 issatisfied, and the allowable range of the phase difference is obtainedto be 0.00038π rad (0.07°) . Therefore, the appropriate range of thephase difference can be 0.48π±0.00038π (rad) (86.4±0.07 (°)), andfurther can be 1.52π±0.00038π (rad) (273.6±0.07 (°).

$\begin{matrix}{{\Delta\; p_{m}} = {\left( {d - d^{2}} \right)/\left\lbrack {100*{\left( N_{0}^{\prime} \right)/V_{0}^{1}}} \right\rbrack}} & (9)\end{matrix}$

From the above examination results, the desirable range of the phasedifference is expressed to be 2π(p_(m)−Δp_(m)) (rad) to 2π(p_(m)+Δp_(m))(rad) or 2π[(1−p_(m))−Δp_(m)] (rad) to 2π[(1−p_(m)) +Δp_(m) (rad) inunits of rad (radian), and can be generally expressed to be 360(p_(m)−Δp_(m)) (°) to 360 (p_(m)+Δp_(m)) (°) or 360[(1−p_(m))−Δp_(m)](°) to 360[(1−p_(m))+Δp_(m)] (°) in units of degrees (°). However, whered represents the duty ratio, p_(m)=d−d² is satisfied, andΔp_(m)=(d−d²)/[20*(N₀′)/V¹ ₀], more desirablyΔp_(m)=3*(d−d²)/[100*(N₀′)/V¹ ₀], and more desirablyΔp_(m)=(d−d²)/[100*(N₀′)/V¹ ₀] is satisfied.

On the other hand, Δp_(m) may be set to satisfy Δp_(m)=0.01*p_(m) basedon the relationship with p_(m). In this way, Δp_(m) may be uniquely setto 1% of p_(m).

From the following experiment and consideration, it can be found thatnoise occurs in a signal obtained by processing, using a lock-inamplifier, a fluorescence signal detected by a fluorescence detectorwhen the sample passes through a fluorescence detection region even whenthe phase difference between flashing of the first excitation lightaccording to the first fluorescence detection device 50 and flashing ofthe second excitation light according to the second fluorescencedetection device 54 is set such that the noise is minimized.

FIGS. 14 and 15 show a relationship between a signal output from thefirst fluorescence detection device 50 and time when a sample was movedinside the channel 12 and passed through a predetermined fluorescencedetection region in the reaction processing apparatus 30 shown in FIG.2. FIG. 14 shows a fluorescence signal output from the firstfluorescence detection device 50 when the sample was moved inside thechannel 12 while the second fluorescence detection device 54 was beingstopped (that is, without flashing the second excitation light source).On the other hand, FIG. 15 shows a fluorescence signal output from thefirst fluorescence detection device 50 when the sample was moved insidethe channel 12 while the second fluorescence detection device 54 wasbeing operated (that is, while flashing the second excitation lightsource).

Both the first excitation light and the second excitation light wereflashed at the same frequency (110 Hz) and the same duty ratio of 0.5(50%), and the phase difference Δφ between the first excitation lightand the second excitation light was set to 0.5π rad (90.0°).Furthermore, each excitation light and fluorescence detector wereindependently arranged with respect to the channel such that theintensity of fluorescence from the sample in the channel 12 wasmaximized.

First, the behavior of a fluorescence signal at the time of the passingof the sample through the fluorescence detection region will bedescribed with reference to FIG. 14. The intensity of a fluorescencesignal shown in FIG. 14 shifts at a baseline over time and rises at acertain time (11× 1/10 seconds). It can be considered that the sampleentered the first fluorescence detection region 12 a at this time.Further, the fluorescence signal shifts to a substantially constantvalue (substantially 14 at arbitrary intensity) over time. It can beconsidered that this corresponds to the time during which the samplehaving a certain length were pas sing through the first fluorescencedetection region 12 a inside the channel 12. Then, at a certain time,the fluorescence signal falls to the baseline again. It can beconsidered that the sample came out of the first fluorescence detectionregion 12 a at this time (18× 1/10 seconds). After that, thefluorescence signal shifts at the baseline.

The above explanation relates to the behavior of a fluorescence signalwhen a sample passes through the first fluorescence detection region 12a only once. In the case of PCR, a sample repeatedly moves in areciprocating manner in a channel 12 and is repeatedly exposed to presettemperature regions of different levels (that is, thermal cycle), andspecific DNA or the like contained in the sample is thereby amplified.

In the case of a sample containing a fluorescent dye, the intensity offluorescence emitted from the sample increases as predetermined DNA orthe like is amplified. Then, by monitoring the maximum value of afluorescence signal obtained when the sample passes through afluorescence detection region with respect to the increasingfluorescence intensity, real-time PCR accompanying amplification of thepredetermined DNA can be realized.

Next, the behavior of a fluorescence signal at the time of the passingof the sample through the fluorescence detection region will bedescribed with reference to FIG. 15. The behavior of the fluorescencesignal shown in FIG. 15 is different from that of the fluorescencesignal shown in FIG. 14. The fluorescence signal shown in FIG. 15exhibits a large overshoot at a rising part and exhibits higherfluorescence intensity than substantially constant fluorescenceintensity shown in the subsequent time. The occurrence of a largeovershoot in a fluorescence signal as described above causes thefluorescence signal to vary, which makes it difficult to monitor theaccurate intensity of the fluorescence signal, and real-time PCR may bethus hindered.

From the above, it is suggested that, in a plurality of combinations ofexcitation light/fluorescence, when the wavelength range correspondingto excitation light belonging to any combination and the wavelengthrange corresponding to fluorescence belonging to other combinationsoverlap, the detection of the fluorescence signal is affected even whenthe lock-in phase difference is optimized. The behavior of thefluorescence signal shown in FIG. 15 may exist even when the flashingphase difference between the excitation light of the first fluorescencedetection device 50 and the excitation light of the second fluorescencedetection device 54 is optimized.

Thus, the present inventors made earnest studies and experiments toreduce such an overshoot of a fluorescence signal and found that thecause for the overshoot lies in the inter-fluorescent point distance tp.More specifically, it was found that in a case where the NA of anoptical system of an optical head for a sample was within apredetermined range, the noise value (Nv) became 0.2 or less, which wasa suitable value, when the inter-fluorescent point distance tp was 4 mmor more.

FIG. 16 is a diagram for explaining an exemplary embodiment of thepresent invention. In the same manner as in the above-describedembodiment, the first optical head 51 and the second optical head 55were arranged side by side such that the fluorescence from the sample 20arranged in the channel 12 of the reaction processing vessel 10 could bedetected. The first optical head 51 includes an objective lens OB1, andthe second optical head 55 includes an objective lens OB2. A firstfluorescence detection region 12 a and a second fluorescence detectionregion 12 b are set in the channel 12. The first optical head 51irradiates the sample 20 located in the first fluorescence detectionregion 12 a with excitation light and receives fluorescence. The secondoptical head 55 irradiates the sample 20 located in the secondfluorescence detection region 12 b with excitation light and receivesfluorescence. The excitation light emitted from the first optical head51 and the excitation light emitted from the second optical head 55 wereflashed both at a frequency of 110 Hz and a duty ratio of 0.5. A lock-inprocess was performed on the fluorescence received by the first opticalhead 51 and the fluorescence received by the second optical head 55 by alock-in amplifier (see FIG. 5) in the subsequent stage so that afluorescence signal was output. Further, regarding the flashing of theexcitation light emitted from the first optical head 51 and theexcitation light emitted from the second optical head 55, the respectivephases were adjusted such that the phase difference therebetween was0.5π rad (90.0°). As shown in FIG. 16, the distance between the centerof the first fluorescence detection region 12 a and the center of thesecond fluorescence detection region 12 b represents theinter-fluorescent point distance tp.

First Exemplary Embodiment

In the first exemplary embodiment, as the objective lens OB1 of thefirst optical head 51 and the objective lens OB2 of the second opticalhead 55, those having a numerical aperture (NA) of 0.23 were used. Thefirst fluorescence detection device corresponds to FAM using acombination of blue excitation/green fluorescence, and the secondfluorescence detection device corresponds to ROX using a combination ofgreen excitation/red fluorescence.

FIG. 17 shows a fluorescence signal output from the first fluorescencedetection device 50 when the inter-fluorescent point distance tp is 4 mmin the first exemplary embodiment. A FAM aqueous solution was used forthe sample. In FIG. 17, the horizontal axis represents time (× 1/10seconds), and the vertical axis represents fluorescence intensity(arbitrary unit). In a fluorescence signal shown in FIG. 17, two peaksappear as one set at approximately constant time intervals. The samplerepeatedly moves in a reciprocating manner in the channel 12 (however,the moving speed was adjusted such that the transit time of the samplethrough the first fluorescence detection region 12 a was about 0.5seconds). Therefore, like the fluorescence signal of FIG. 17, the valueof fluorescence intensity in an outward route and the value offluorescence intensity in a return route appear as a set.

Second Exemplary Embodiment

In the second exemplary embodiment, as the objective lens OB1 of thefirst optical head 51 and the objective lens OB2 of the second opticalhead 55, those having a numerical aperture (NA) of 0.18 were used.

Third Exemplary Embodiment

In the third exemplary embodiment, as the objective lens OB1 of thefirst optical head 51 and the objective lens OB2 of the second opticalhead 55, those having a numerical aperture (NA) of 0.12 were used.

Fourth Exemplary Embodiment

In the fourth exemplary embodiment, as the objective lens OB1 of thefirst optical head 51 and the objective lens OB2 of the second opticalhead 55, those having a numerical aperture (NA) of 0.07 were used.

In the first through fourth exemplary embodiments, the inter-fluorescentpoint distance tp was changed to 2.5 mm, 2.75 mm, 3 mm, 3.5 mm, 4 mm,4.5 mm, and 5 mm, and a fluorescence signal output from the firstfluorescence detection device 50 was obtained for each inter-fluorescentpoint distance tp. In order to evaluate the variation in thefluorescence intensity obtained according to the reciprocating movementof the sample, the standard deviation of the maximum value of thefluorescence intensity at each peak obtained by 50 occurrences of thereciprocating movement of the sample was calculated as a noise value Nvand used as an index.

The following table summarizes the relationship between theinter-fluorescent point distance tp (mm) and the noise value Nv obtainedfor the first through fourth exemplary embodiments.

TABLE 1 tp NA [mm] 0.23 0.18 0.12 0.07 2.5 1.715 1.417 1.162 0.281 2.751.204 1.131 0.813 0.162 3 0.794 0.772 0.705 0.161 3.5 0.458 0.454 0.2350.136 4 0.155 0.175 0.162 0.119 4.5 0.171 0.139 0.172 0.131 5 0.1770.177 0.128 0.123

Regarding the first exemplary embodiment where the numerical aperture(NA) was 0.23, when the inter-fluorescent point distance tp was 4 mm to5 mm, the noise value Nv was less than 0.2, and a good result wasobtained. Regarding the second exemplary embodiment where the numericalaperture (NA) was 0.18, when the inter-fluorescent point distance tp was4 mm to 5 mm, the noise value Nv was less than 0.2, and a good resultwas obtained. Regarding the third exemplary embodiment where thenumerical aperture (NA) was 0.12, when the inter-fluorescent pointdistance tp was 3.5 mm to 5 mm, the noise value Nv was less than 0.3,and a good result was obtained, and, when the inter-fluorescent pointdistance tp was 4 mm to 5 mm, the noise value Nv was less than 0.2, anda better result was obtained. Regarding the fourth exemplary embodimentwhere the numerical aperture (NA) was 0.07, when the inter-fluorescentpoint distance tp was 2.5 mm to 5 mm, the noise value Nv was less than0.3, and a good result was obtained, and, when the inter-fluorescentpoint distance tp was 2.75 mm to 5 mm, the noise value Nv was less than0.2, and a better result was obtained. Based on these experimentalresults, the present inventors found that the noise value Nv became 0.2or less, which was a suitable value, when the inter-fluorescent pointdistance tp was 4 mm or more in a case where the numerical aperture NAof the optical head was in a range of 0.07 to 0.23.

In order to confirm the effect of the present exemplary embodiments, PCRwas actually performed on the samples shown in the following table usingthe reaction processing apparatus 30 shown in FIG. 2, and a fluorescencesignal was measured in real time. In an attempt to detect Vero toxinVT1, PCR samples were prepared using a KAPA3G Plant PCR kit, which is aPCR enzyme from KAPA Biosystems, in the manner shown in the table below.

TABLE 2 Chemical Final agents, Concentra- etc. tion Remarks enzyme  0.1U/μL KAPA 3G Plant (manufactured by KAPA Biosystems) Primer F  720 nM5′-GGA TAA TTT GTT TGC AGT TGA TGT-3′ (SEQ ID NO: 1) (manufactured byNIHON GENE RESEARCH LABORATORIES Inc.) Primer R  720 nM 5′-CAA ATC CTGTCA CAT ATA AAT TAT TTC GT-3′ (SEQ ID NO: 2) (manufactured by NIHON GENERESEARCH LABORATORIES Inc.) Probe  240 nM 5′-CCG TAG ATT ATT AAA CCG CCCTTC CTC TGG A-3′ (SEQ ID NO: 3) FAM is used for fluorescent dye andquencher is of a dark type (manufactured by NIHON GENE RESEARCHLABORATORIES Inc.) Additional 1.25 mM attached to KAPA 3G Plant MgBuffer + In accordance with the KAPA 3G Plant Water manual, buffer andwater are blended such that the concentration of the attached buffer islowered down to ½ with respect to the total reagent.

PCR was performed for the first exemplary embodiment in which thenumerical aperture NA of the objective lens was set to 0.23. FIG. 18shows a PCR amplification result in the first exemplary embodiment. InFIG. 18, the horizontal axis represents the number of cycles, and thevertical axis represents the fluorescence intensity (arbitrary unit).Using the reaction processing apparatus 30 described above, theintensity of a fluorescence signal detected by the first fluorescencedetection device 50 with respect to the number of cycles was measured.As a specimen in the sample was amplified, the fluorescence intensityincreased. As shown in FIG. 18, the fluorescence intensity sharply risesfrom around 30 cycles. Such a sharp rise in fluorescence intensityindicates that the specimen in the sample is amplified, and it can befound that good PCR can be performed when the first exemplary embodimentis used.

Next, a comparative example is shown. In the comparative example, theinter-fluorescent point distance tp was set to 3 mm, and the otherconditions were set to be the same as those in the first exemplaryembodiment (see FIG. 17).

FIG. 19 shows a fluorescence signal output from the first fluorescencedetection device 50 in the comparative example. Comparing thefluorescence signal shown in FIG. 19 with the case of the firstexemplary embodiment shown in FIG. 17, it can be found that a very largeovershoot occurred in the comparative example shown in FIG. 19.

FIG. 20 shows the amplification result of PCR in the comparativeexample. When the amplification result of PCR shown in FIG. 20 iscompared with the case of the first exemplary embodiment shown in FIG.18, it can be found that the variation in fluorescence intensity is verylarge in the comparative example shown in FIG. 20. When the variation inthe fluorescence intensity is large as described above, it is difficultto detect the rise of the fluorescence intensity, and thus the accuracyof the real-time PCR may decrease. From the comparison with thiscomparative example, the superiority of the present exemplaryembodiments was demonstrated.

FIG. 21 is a diagram for explaining a reaction processing apparatus 130according to another embodiment of the present invention. The reactionprocessing apparatus 130 shown in FIG. 21 is different from the reactionprocessing apparatus 30 shown in FIG. 2 in that the reaction processingapparatus 130 is provided with three fluorescence detection devices (afirst fluorescence detection device 131, a second fluorescence detectiondevice 132, and a third fluorescence detection device 133). In FIG. 21,only the three fluorescence detection devices and a part of the reactionprocessing vessel 10 are shown, and the illustration of the otherstructures is omitted.

The first fluorescence detection device 131 is formed to be able todetect fluorescence from a sample containing FAM as a fluorescent dye.The first fluorescence detection device 131 includes a first opticalhead 134, irradiates the first fluorescence detection region 12 a of thechannel 12 with first excitation light (blue light) having a centerwavelength of about 470 nm and a wavelength range of about 450 to 490nm, and detects first fluorescence (green light) having a centerwavelength of about 530 nm and a wavelength range of about 510 to 550nm.

The second fluorescence detection device 132 is formed to be able todetect fluorescence from a sample containing ROX as a fluorescent dye.The second fluorescence detection device 132 includes a second opticalhead 135, irradiates the second fluorescence detection region 12 b ofthe channel 12 with second excitation light (green light) having acenter wavelength of about 530 nm and a wavelength range of about 510 to550 nm, and detects second fluorescence (red light) having a centerwavelength of about 610 nm and a wavelength range of about 580 to 640nm.

The third fluorescence detection device 133 is formed to be able todetect fluorescence from a sample containing Cy5 as a fluorescent dye.The third fluorescence detection device 133 includes a third opticalhead 136, irradiates the third fluorescence detection region 12 c of thechannel 12 with third excitation light (red light) having a centerwavelength of about 630 nm and a wavelength range of about 610 to 650nm, and detects third fluorescence (infrared light) having a centerwavelength of about 690 nm and a wavelength range of about 660 to 720nm.

The reaction processing apparatus 130 according to the presentembodiment is characterized by the arrangement order of the opticalheads of the three fluorescence detection devices. More specifically,the optical heads are arranged in the order of the second optical head135 according to the second fluorescence detection device 132, the firstoptical head 134 according to the first fluorescence detection device131, and the third optical head 136 according to the third fluorescencedetection device 133 from the low temperature region side. In otherwords, the first optical head 134 is arranged in the center, the secondoptical head 135 is arranged on the low temperature region side of thefirst optical head 134, and the third optical head 136 is arranged onthe high temperature region side of the first optical head 134. Theposition of the second fluorescence detection device 132 and theposition of the third fluorescence detection device 133 may be switched.That is, the third optical head 136 may be arranged on the lowtemperature region side of the first optical head 134, and the secondoptical head 135 may be arranged on the high temperature region side ofthe first optical head 134.

As mentioned above, the interference between the fluorescence detectiondevices is caused by the overlap of the wavelength range of excitationlight and the wavelength range of fluorescence. Therefore, whenarranging a plurality of optical heads side by side, an arrangement isavoided in which the optical heads whose wavelength range of excitationlight and the wavelength range of fluorescence overlap each other areadjacent to each other. For example, if the second optical head 135 isarranged in the center and the first optical head 134 and the thirdoptical head 136 are arranged on the respective sides thereof, thewavelength range of the second excitation light according to the secondoptical head 135 (about 510 to 550 nm) and the wavelength range of thefirst fluorescent light of the first optical head 134 (about 510 to 550nm) overlap. Further, the wavelength range of the second fluorescence(about 580 to 640 nm) according to the second optical head 135 and thewavelength range of the third fluorescence (about 610 to 650 nm)according to the third optical head 136 partially overlap. In this case,interference is likely to occur between the first fluorescence detectiondevice 131 and the second fluorescence detection device 132 and betweenthe second fluorescence detection device 132 and the third fluorescencedetection device 133.

On the other hand, when the first optical head 134 is arranged in thecenter and the second optical head 135 and the third optical head 136are arranged on the respective sides thereof as in the presentembodiment, the second optical head 135 and the third optical head 136are separated. Therefore, interference between the second fluorescencedetection device 132 and the third fluorescence detection device 133 canbe made less likely to occur.

Alternatively, the third optical head 136 may be arranged in the center,and the first optical head 134 and the second optical head 135 may bearranged on the respective sides thereof. In this case also, the firstoptical head 134 and the second optical head 135 are separated from eachother. Therefore, interference between the first fluorescence detectiondevice 131 and the second fluorescence detection device 132 can be madeless likely to occur.

In the reaction processing apparatus, there are cases where thefluctuation of the fluorescence intensity according to any one of theplurality of fluorescence detection devices is used as a parameter forcontrolling the movement of the sample (displacement and stopping of thesample) that repeatedly moves in a reciprocating manner in the channel.The optical head of the fluorescence detection device used for such apurpose is desirably arranged at a substantially intermediate point ofthe connection region between the high temperature region and the lowtemperature region in the channel. If the optical head used forcontrolling the movement of the sample is arranged closer to either sideof the high temperature region or the low temperature region of theconnection region of the channel than the other, the control of theliquid feeding and stopping of the feeding may become troublesome.Arranging the optical head used for controlling the movement of thesample substantially in the middle of the connection region of thechannel makes it easy to control the liquid feeding and stopping of thesample. The ease of control also leads to an improvement in accuracy.

On the other hand, in a samples that is subjected to a reaction processsuch as PCR, it is often the case that a fluorescent dye that excitesthe sample with excitation light whose wavelength centers on about 470nm, such as FAM, is added. By the excitation using light having awavelength of about 470 nm, the corresponding fluorescence necessarilyincludes light having a wavelength of about 500 to 560 nm. Thiscorresponds to the specification of the first fluorescence detectiondevice 131, and as a result, a fluorescence detection device that hassuch excitation light/fluorescence wavelength characteristics is oftenused in a reaction processing apparatus.

Due to the above-mentioned circumstances, it is appropriate that thefirst optical head 134, which is arranged in the center of the threeoptical heads, is arranged at a substantially intermediate point C ofthe connection region of the channel 12. The above-mentionedcircumstances also apply in the above-mentioned reaction processingapparatus 30 including only two fluorescence detection devices. That is,in the reaction processing apparatus 30 shown in FIG. 2, the firstoptical head 51 may be arranged at a substantially intermediate point Cof the connection region of the channel 12.

Described above is an explanation based on the embodiments of thepresent invention. These embodiments are intended to be illustrativeonly, and it will be obvious to those skilled in the art that variousmodifications to constituting elements and processes could be developedand that such modifications are also within the scope of the presentinvention.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a polymerase chain reaction(PCR).

Sequence Listing Free Text

Sequence number 1: forward PCR primer

Sequence number 2: reverse PCR primer

Sequence number 3: Probe

[Sequence Listing] NSG-70058WO Sequence Listing.txt

What is claimed is:
 1. A reaction processing apparatus comprising: areaction processing vessel including a channel where a sample moves; afirst fluorescence detection device irradiating a sample inside a firstfluorescence detection region provided in the channel with firstexcitation light, detecting first fluorescence produced from the sampleby the irradiation with the first excitation light, the firstfluorescence detection device including a first optical head that emitsthe first excitation light and receives the first fluorescence; and asecond fluorescence detection device irradiating a sample inside asecond fluorescence detection region provided in the channel with secondexcitation light, detecting second fluorescence produced from the sampleby the irradiation with the second excitation light, the secondfluorescence detection device including a second optical head that emitsthe second excitation light and receives the second fluorescence,wherein the wavelength range of the first fluorescence and thewavelength range of the second excitation light overlap with each otherat least partially, and given that the standard deviation of the maximumvalue of the intensity of the first fluorescence received by the firstoptical head is denoted as Nv, Nv is less than 0.3.
 2. The reactionprocessing apparatus according to claim 1, wherein the first opticalhead includes a first lens having a numerical aperture of 0.07 to 0.23,and the second optical head includes a second lens having a numericalaperture of 0.07 to 0.23.
 3. The reaction processing apparatus accordingto claim 1, wherein given that the distance between the center of thefirst fluorescence detection region and the center of the secondfluorescence detection region is denoted as tp, tp is more than 4 mm. 4.The reaction processing apparatus according to claim 3, wherein Nv isless than 0.2.
 5. The reaction processing apparatus according to claim1, wherein the first fluorescence includes light with a wavelength in awavelength range of 510 to 550 nm; and the second excitation lightincludes light with a wavelength in a wavelength range of 510 to 550 nm.